 |
 John
Torrey was considered the leader of
botanists in America during his lifetime. He
published three comprehensive catalogs of North
American flora, and was one of the first American
botanists to arrange plants by families. |
 Rubik's
Cube was invented by a Hungarian
professor in 1974, as a mental exercise for his
students. The cubic puzzle quickly became a craze
in Hungary, then spread across Europe, and by
1980 was the top-selling toy in the United
States. |
 Clyde
William Tombaugh was hired by the
Lowell Observatory after sending detailed
drawings of observations he had made of Mars and
Jupiter using a homemade telescope. It was at
Lowell where, in 1930, he discovered a planet
orbiting beyond Neptune; that planet was
subsequently named Pluto. |
 A Barometer
is an instrument for
measuring atmospheric pressure. The atmosphere
exerts a pressure because air has weight and is
being pulled to the earth by the force of
gravity. For this reason atmospheric pressure
depends on the height of air above the point at
which it is being measured and is lower on top of
a mountain than it is at sea level. |
 Agate
forms when silica in
solution seeps into a cavity in lava and hardens
in successive layers. Chemically it consists of
silicon and oxygen, SiO2. |
 Jean
Baptiste Lamarck believed that if an
animal began using an organ more than it had in
the past, the size of that organ would increase
during its lifetime. For example,
if a giraffe stretched its neck to reach higher
leaves, a "nervous fluid" would flow
into its neck and make it longer over time. |
 Leaves
are the main food-making
parts of almost all plants. They capture energy
from sunlight and use it to make food out of
water from the soil and carbon dioxide. This food
provides plants with energy to grow, to produce
flowers and seeds, and to carry on all their
other activities. |
 Troupial
(Icterus icterus)
This fairly large member of the oriole family is
found in northern and central South America.
Unlike other orioles it does not build its own
nest, relying instead on nests stolen from other
birds. It is the national bird of Venezuela. |
 Hearing
Man hears sounds when any vibrating
object pushes air molecules at a rate between 15
and 15,000 vibrations per second. Sound waves are
turned into nerve impulses inside the cochlea. |
